Dabbing Pulsed Welding System And Method

ABSTRACT

A pulsed welding regime includes a peak phase in which energy is added to an electrode and a weld puddle, and a molten ball begins to detach from the electrode, followed by a dabbing phase in which current is significantly reduced to place the ball in the weld puddle with addition of little or no energy. The resulting short circuit clears and the system proceeds to a background phase. The current in the dabbing phase is lower than the current during the background phase. The process may be specifically adapted for particular welding wires, and may be particularly well suited for use with cored wires. The dabbing phase allows for lower energy to be transferred to the sheath of such wires, and resets the arc length after each pulse cycle.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to and benefit of U.S. ProvisionalPatent Application No. 61/736,393, entitled “Dabbing Pulsed WeldingSystem and Method”, filed Dec. 12, 2012, and U.S. Non-Provisional patentapplication Ser. No. 14/076,705, entitled “Dabbing Pulsed Welding Systemand Method”, filed Nov. 11, 2013, which are herein incorporated byreference in its entirety for all purposes.

BACKGROUND

The invention relates generally to welders, and more particularly to awelder configured to perform a welding operation in which a pulsedwaveform is applied to welding wire as the wire is advanced from awelding torch.

A wide range of welding systems and welding control regimes have beenimplemented for various purposes. In continuous welding operations,metal inert gas (MIG) techniques allow for formation of a continuingweld bead by feeding welding wire shielded by inert gas from a weldingtorch. Electrical power is applied to the welding wire and a circuit iscompleted through the workpiece to sustain an arc that melts the wireand the workpiece to form the desired weld.

Advanced forms of MIG welding are based upon generation of pulsed powerin the welding power supply. That is, various pulsed regimes may becarried out in which current and/or voltage pulses are commanded by thepower supply control circuitry to regulate the formation and depositionof metal droplets from the welding wire, to sustain a desired heatingand cooling profile of the weld pool, to control shorting between thewire and the weld pool, and so forth.

While very effective in many applications, such pulsed regimes may besubject to drawbacks. For example, depending upon the transfer mode, theprocesses may either limit travel speed, create excessive spatter(requiring timely cleanup of welded workpieces), provide less thanoptimal penetration, or any combination of these and other effects.Moreover, certain pulsed processes, such as ones operating in a spraymode of material transfer, may run excessively hot for particularapplications. Others, such as short circuit processes, may run cooler,but may again produce spatter and other unwanted weld effects.

Moreover, in certain welding situations and with certain weldingelectrodes, pulsed welding processes that are trained to implementcyclic short circuits between the electrode and the workpiece may addexcessive energy to the weld. For example, with cored wire electrodes,the electrode may be heated by excessive current added to the wire,particularly insomuch as the weld current tends to flow through the wiresheath, which can more easily melt than solid wires. As a result, thearc may flare (grow long). However, for spanning gaps, reducingburn-through, and increasing travel speeds, it may be desirable tomaintain the arc length at a minimum. Unfortunately, this causes thewire to short to the progressing weld puddle and requires additionalcurrent to clear short circuits, again leading to heating of cored wiresheaths, and causing the arc to flare.

There is a need, therefore, for improved welding strategies that allowfor welding in pulsed waveform regimes while improving weld quality andflexibility.

BRIEF DESCRIPTION

The present invention provides welding systems designed to respond tosuch needs. In accordance with an exemplary implementation, a weldingsystem comprises processing circuitry configured to provide a controlwaveform comprising a peak phase followed immediately by a dabbing phasefollowed by a background phase; and power conversion circuitryconfigured to provide welding power output based upon the controlwaveform.

The invention also provides methods for welding, such as, in accordancewith one aspect, generating a waveform for welding power output, thewaveform comprising a peak phase followed immediately by a dabbing phasefollowed by a background phase; and converting incoming power to weldingpower based upon the control waveform.

DRAWINGS

FIG. 1 is a diagrammatical representation of an exemplary MIG weldingsystem illustrating a power supply coupled to a wire feeder forperforming pulsed welding operations in accordance with aspects of thepresent techniques;

FIG. 2 is a diagrammatical representation of exemplary control circuitrycomponents for a welding power supply of the type shown in FIG. 1;

FIG. 3 is a graphical representation of an exemplary waveform fordabbing molten metal from a welding electrode into a weld puddle inaccordance with the present techniques;

FIG. 4 is a graphical representation of voltages and currents in aseries of pulses of such a waveform during an actual implementation;

FIG. 5 is a flow chart illustrating certain control logic inimplementing such a welding regime;

FIG. 6 is a graphical representation of another exemplary waveform fordabbing molten metal from a welding electrode into a weld puddle inaccordance with the present techniques;

FIG. 7 is a flow chart illustrating certain control logic inimplementing the welding regime of FIG. 6; and

FIG. 8 is a flow chart illustrating certain control logic that generatesa power off signal in accordance with the present techniques.

DETAILED DESCRIPTION

Turning now to the drawings, and referring first to FIG. 1, an exemplarywelding system is illustrated as including a power supply 10 and a wirefeeder 12 coupled to one another via conductors or conduits 14. In theillustrated embodiment the power supply 10 is separate from the wirefeeder 12, such that the wire feeder may be positioned at some distancefrom the power supply near a welding location. However, it should beunderstood that the wire feeder, in some implementations, may beintegral with the power supply. In such cases, the conduits 14 would beinternal to the system. In embodiments in which the wire feeder isseparate from the power supply, terminals are typically provided on thepower supply and on the wire feeder to allow the conductors or conduitsto be coupled to the systems so as to allow for power and gas to beprovided to the wire feeder from the power supply, and to allow data tobe exchanged between the two devices.

The system is designed to provide wire, power and shielding gas to awelding torch 16. As will be appreciated by those skilled in the art,the welding torch may be of many different types, and typically allowsfor the feed of a welding wire and gas to a location adjacent to aworkpiece 18 where a weld is to be formed to join two or more pieces ofmetal. A second conductor is typically run to the welding workpiece soas to complete an electrical circuit between the power supply and theworkpiece.

The system is designed to allow for data settings to be selected by theoperator, particularly via an operator interface 20 provided on thepower supply. The operator interface will typically be incorporated intoa front faceplate of the power supply, and may allow for selection ofsettings such as the weld process, the type of wire to be used, voltageand current settings, and so forth. In particular, the system isdesigned to allow for MIG welding with various steels, aluminums, orother welding wire that is channeled through the torch. These weldsettings are communicated to control circuitry 22 within the powersupply. The system may be particularly adapted to implement weldingregimes designed for certain electrode types, such as cored electrodes.

The control circuitry, described in greater detail below, operates tocontrol generation of welding power output that is applied to thewelding wire for carrying out the desired welding operation. In certainpresently contemplated embodiments, for example, the control circuitrymay be adapted to regulate a pulsed MIG welding regime that “dabs” orpromotes short circuit transfer of molten metal to a progressing weldpuddle without adding excessive energy to the weld or electrode. In“short circuit” modes, droplets of molten material form on the weldingwire under the influence of heating by the welding arc, and these areperiodically transferred to the weld pool by contact or short circuitsbetween the wire and droplets and the weld pool. “Pulsed welding” or“pulsed MIG welding” refers to techniques in which a pulsed powerwaveform is generated, such as to control deposition of droplets ofmetal into the progressing weld puddle. In a particular embodiment ofthe invention, a specialized pulsed welding regime may be implemented inwhich pulses are generated that have characteristics of both shortcircuit welding and spray welding, in a type of “hybrid” transfer modeas described in U.S. patent application Ser. No. 13/655,174, entitled“Hybrid Pulsed-Short Circuit Welding Regime”, filed by Hutchison et al.,on Oct. 18, 2012, which is hereby incorporated by reference into thepresent disclosure.

The control circuitry is thus coupled to power conversion circuitry 24.This power conversion circuitry is adapted to create the output power,such as pulsed waveforms that will ultimately be applied to the weldingwire at the torch. Various power conversion circuits may be employed,including choppers, boost circuitry, buck circuitry, inverters,converters, and so forth. The configuration of such circuitry may be oftypes generally known in the art in and of itself. The power conversioncircuitry 24 is coupled to a source of electrical power as indicated byarrow 26. The power applied to the power conversion circuitry 24 mayoriginate in the power grid, although other sources of power may also beused, such as power generated by an engine-driven generator, batteries,fuel cells or other alternative sources. Finally, the power supplyillustrated in FIG. 1 includes interface circuitry 28 designed to allowthe control circuitry 22 to exchange signals with the wire feeder 12.

The wire feeder 12 includes complimentary interface circuitry 30 that iscoupled to the interface circuitry 28. In some embodiments, multi-pininterfaces may be provided on both components and a multi-conductorcable run between the interface circuitry to allow for such informationas wire feed speeds, processes, selected currents, voltages or powerlevels, and so forth to be set on either the power supply 10, the wirefeeder 12, or both.

The wire feeder 12 also includes control circuitry 32 coupled to theinterface circuitry 30. As described more fully below, the controlcircuitry 32 allows for wire feed speeds to be controlled in accordancewith operator selections, and permits these settings to be fed back tothe power supply via the interface circuitry. The control circuitry 32is coupled to an operator interface 34 on the wire feeder that allowsselection of one or more welding parameters, particularly wire feedspeed. The operator interface may also allow for selection of such weldparameters as the process, the type of wire utilized, current, voltageor power settings, and so forth. The control circuitry 32 is alsocoupled to gas control valving 36 which regulates the flow of shieldinggas to the torch. In general, such gas is provided at the time ofwelding, and may be turned on immediately preceding the weld and for ashort time following the weld. The gas applied to the gas controlvalving 36 is typically provided in the form of pressurized bottles, asrepresented by reference numeral 38.

The wire feeder 12 includes components for feeding wire to the weldingtorch and thereby to the welding application, under the control ofcontrol circuitry 36. For example, one or more spools of welding wire 40are housed in the wire feeder. Welding wire 42 is unspooled from thespools and is progressively fed to the torch. The spool may beassociated with a clutch 44 that disengages the spool when wire is to befed to the torch. The clutch may also be regulated to maintain a minimumfriction level to avoid free spinning of the spool. A feed motor 46 isprovided that engages with feed rollers 48 to push wire from the wirefeeder towards the torch. In practice, one of the rollers 48 ismechanically coupled to the motor and is rotated by the motor to drivethe wire from the wire feeder, while the mating roller is biased towardsthe wire to maintain good contact between the two rollers and the wire.Some systems may include multiple rollers of this type. Finally, atachometer 50 may be provided for detecting the speed of the motor 46,the rollers 48, or any other associated component so as to provide anindication of the actual wire feed speed. Signals from the tachometerare fed back to the control circuitry 36, such as for calibration asdescribed below.

It should be noted that other system arrangements and input schemes mayalso be implemented. For example, the welding wire may be fed from abulk storage container (e.g., a drum) or from one or more spools outsideof the wire feeder. Similarly, the wire may be fed from a “spool gun” inwhich the spool is mounted on or near the welding torch. As notedherein, the wire feed speed settings may be input via the operator input34 on the wire feeder or on the operator interface 20 of the powersupply, or both. In systems having wire feed speed adjustments on thewelding torch, this may be the input used for the setting.

Power from the power supply is applied to the wire, typically by meansof a welding cable 52 in a conventional manner. Similarly, shielding gasis fed through the wire feeder and the welding cable 52. During weldingoperations, the wire is advanced through the welding cable jackettowards the torch 16. Within the torch, an additional pull motor 54 maybe provided with an associated drive roller, particularly for aluminumalloy welding wires. The motor 54 is regulated to provide the desiredwire feed speed as described more fully below. A trigger switch 56 onthe torch provides a signal that is fed back to the wire feeder andtherefrom back to the power supply to enable the welding process to bestarted and stopped by the operator. That is, upon depression of thetrigger switch, gas flow is begun, wire is advanced, power is applied tothe welding cable 52 and through the torch to the advancing weldingwire. These processes are also described in greater detail below.Finally, a workpiece cable and clamp 58 allow for closing an electricalcircuit from the power supply through the welding torch, the electrode(wire), and the workpiece for maintaining the welding arc duringoperation.

It should be noted throughout the present discussion that while the wirefeed speed may be “set” by the operator, the actual speed commanded bythe control circuitry will typically vary during welding for manyreasons. For example, automated algorithms for “run in” (initial feed ofwire for arc initiation) may use speeds derived from the set speed.Similarly, various ramped increases and decreases in wire feed speed maybe commanded during welding. Other welding processes may call for“cratering” phases in which wire feed speed is altered to filldepressions following a weld. Still further, in pulsed welding regimes,the wire feed speed may be altered periodically or cyclically.

FIG. 2 illustrates an exemplary embodiment for the control circuitry 22designed to function in a system of the type illustrated in FIG. 1. Theoverall circuitry, designated here by reference numeral 60, includes theoperator interface 20 discussed above and interface circuitry 28 forcommunication of parameters to and from downstream components such as awirefeeder, a welding torch, and various sensors and/or actuators. Thecircuitry includes processing circuitry 62 which itself may comprise oneor more application-specific or general purpose processors, designed tocarry out welding regimes, make computations for waveforms implementedin welding regimes, and so forth. The processing circuitry is associatedwith driver circuitry 64 which converts control signals from theprocessing to drive signals that are applied to power electronicswitches of the power conversion circuitry 24. In general, the drivercircuitry reacts to such control signals from the processing circuitryto allow the power conversion circuitry to generate controlled waveformsfor pulsed welding regimes of the type described in the presentdisclosure. The processing circuitry 62 will also be associated withmemory circuitry 66 which may consist of one or more types of permanentand temporary data storage, such as for providing the welding regimesimplemented, storing welding parameters, storing weld settings, storingerror logs, and so forth.

More complete descriptions of certain state machines for welding areprovided, for example, in U.S. Pat. No. 6,747,247, entitled“Welding-Type Power Supply With A State-Based Controller”, issued toHolverson et al. on Sep. 19, 2001; U.S. Pat. No. 7,002,103, entitled“Welding-Type Power Supply With A State-Based Controller”, issued toHolverson et al. on May 7, 2004; U.S. Pat. No. 7,307,240, entitled“Welding-Type Power Supply With A State-Based Controller”, issued toHolverson et al. on Feb. 3, 2006; and U.S. Pat. No. 6,670,579, entitled“Welding-Type System With Network And Multiple Level Messaging BetweenComponents”, issued to Davidson et al. on Sep. 19, 2001, all of whichare incorporated into the present disclosure by reference.

FIG. 3 generally illustrates an exemplary waveform for a weldingtechnique in which molten metal from the welding electrode is “dabbed”into the weld puddle by controlled reduction of weld current applied tothe electrode. In the present context, the term “dab” or “dabbed” or“dabbing” is intended to convey that a relatively hard short is avoided,and that a very brief short circuit may be established once the moltenmaterial is already detaching from the electrode and transferring to theweld puddle. The metal is thus transferred without adding excessiveenergy that might be required if harder or longer term short circuitswere employed. In most cycles of the resulting welding process, nospecial short clearing sequence will be needed, although such sequencesmay be programmed and ready to be implemented in case a longer or morestubborn short circuit does occur. Once the metal is transferred by the“dab”, the arc length is effectively reset, allowing the electrode to“run tighter” or more close to the weld puddle to maintain a short arc.As described below, because the molten material (e.g., a ball of metal)is already detaching after a voltage and/or current peak, little or nocurrent is added to clear the short circuit. The result is a very lowvoltage arc (i.e., short arc length) and a stable arc with minimumheating of the sheath when cored wires are used.

The waveform shown in FIG. 3, designated generally by reference numeral68, implements several phases, including a background phase 70, a peakphase 72, and a dabbing (brief short circuit) phase 74. A short clearingroutine 76 may be included in case a harder short occurs and additionalcurrent is needed to clear the short. However, in many or most cycles ofthe waveform, this routine may not be needed, further reducing theenergy added to the weld and wire.

The waveform 68 shown in FIG. 3 is a current waveform, although, asdiscussed below with respect to FIG. 4, a voltage waveform exhibitssimilar behavior and phases. In the exemplary embodiment of FIG. 3, forexample, during the background and peak phases, a closed-loop controlregime is implemented in which a target voltage is maintained, andcurrent varies to maintain the voltage at the desired levels. During theintermediate ramps, a closed-loop control regime may maintain currentsand current ramps at desired levels. The system may thus cyclicallytransition between current and voltage control to implement the desiredwaveform.

By way of example, in the waveform illustrated in FIG. 3, during thebackground phase 70, a current in a range of approximately 25-125 amps(e.g., approximately 115 amps as illustrated in FIG. 3) may bemaintained, although again this may vary to meet a desired backgroundvoltage level. During the peak phase 72, then, a current in a range ofapproximately 250-450 amps (e.g., approximately 400 amps as illustratedin FIG. 3) may be maintained, varying again if the voltage isclosed-loop controlled. The current during the dabbing phase 74 may bein a range of approximately 15-25 amps (e.g., approximately 25 amps asillustrated in FIG. 3). The durations of these and other phases of thewaveform may also be programmed to allow for energy transfer, formationof a molten ball on the electrode, transfer of the ball, and so forth.It should be noted that the particular voltages, currents, and durationsimplemented may depend upon such factors as the electrode type used, theelectrode size, the wire feed speed, the travel speed, and so forth.

It may be noted that the terms “peak”, “dabbing”, and “background” havebeen used in the present discussion to convey the phases of the waveformbased upon the short “dabbing” phase, as opposed to other pulsed weldingregimes. In other programming language, these phases might correspond to“ball”, “back”, and “pre-short”, although those phases in conventionalsystems are not programmed to implement the low-energy dabbingcontemplated by the present techniques.

FIG. 4 illustrates several cycles of a dabbing pulsed waveform basedupon programming of the type illustrated in FIG. 3. In FIG. 4, a voltagewaveform is indicated by reference numeral 78, while a current waveformis indicated by the reference numeral 80. As can be seen in the voltagewaveform, each cycle includes a voltage background 82 during which anarc is ongoing and energy is added to the electrode and weld puddle (andto the surrounding workpiece). This background is followed by a peak 84during which molten metal created during the background phase istransferred to the weld puddle. In a present implementation, both thebackground and peak phases are closed-loop voltage controlled, resultingin variation in the current during the corresponding phases, asdiscussed below. The rapid drop in the voltage, as indicated byreference numeral 86 is indicative of a brief short circuit as themolten metal is transferred to the weld puddle. This phase is generallyrapid and a “hard short” may be avoided by using a reduced currenttarget during this time.

On the corresponding current waveform 80, the background phase isindicated by reference numeral 88, while the peak phase is indicated byreference numeral 90. It may be noted that the current does vary duringthese phases as the system attempts to maintain the target or programmedvoltage. As noted above, then, a reduced dabbing current target is usedto deposit the molten ball in the weld puddle with reduced energy input,as indicated by reference numeral 92. In certain cycles, a “wet” phase94 may be implemented to assist in clearing the short circuit. Moreover,in cycles when short circuits do not easily clear, a more elevatedcurrent may be used to force the short circuit to clear, as indicated byreference numeral 96.

It should be noted that in the waveforms illustrated in FIGS. 3 and 4,the resulting “dabbing” regime differs from conventional short circuitwelding waveforms. In particular, in conventional welding regimes a peakphase is followed by a “knee” in which the current is maintained at alevel above the subsequent background level. The knee may aid inavoiding short circuits, if desired. If not desired, the knee may bereduced in duration and the waveform may return more quickly to thebackground level.

In the present technique, on the other hand, a current lower than thebackground current level is targeted immediately after the peak phase.For example, while the background current level may be on the order of25-125 amps, the dabbing current may be less than approximately 25 amps,for example, on the order of 15-25 amps. The duration of the dabbing maybe very short, such as on the order of 1-5 ms. This reduced currentallows the short circuit transfer of the molten ball with the additionof very little energy, thus avoiding overheating the electrode. The arclength is thus reset and excessive stickout and flaring of the arc areavoided.

FIG. 5 illustrates exemplary control logic for implementing the dabbingregime. The logic, indicated generally by reference numeral 98, iscyclical, but may be considered to begin with maintaining the backgroundphase (constant voltage in a current implementation), as indicated byreference numeral 100. During this phase the arc is established andenergy is added to the electrode and weld puddle. Then the peak phase isimplemented (again a constant voltage in the current implementation), asindicated by reference numeral 102. This phase does the majority of thedetachment of the molten metal (i.e., the molten ball is being pushedoff the end of the wire due to the arc force generated by the highcurrents), but the ball does not generally detach during this phase (butremains attached by a trailing tail). The ball detaches during the shortthat follows in the dabbing phase, but because the ball is alreadyextended away from the end of the electrode, little or no additionalenergy is required to remove the short circuit. At step 104, the currentis reduced to the target minimum to dab the molten ball into the weldpuddle with the addition of very little energy. If needed, a shortcircuit routine may be implemented, as indicated by reference numeral106, as when the current and voltage levels indicate that a shortcircuit persists and did not clear following the dabbing current. Atstep 108, then, the control returns to the background levels, and thecycle may be repeated.

It should be noted that in some implementations the dabbing may beperformed in different ways than by a low current target following thepeak phase. For example, an output short circuit may be created via aswitch to quickly reduce the current between the electrode and theworkpiece and weld puddle. Similarly, the output power may be switchedoff for a short duration following the peak phase in order to extinguishthe arc or at least to add little or no energy.

As mentioned above with respect to FIGS. 3 and 4, certain embodimentsdescribed herein differ from conventional pulsed welding waveforms inthat a knee phase (at a current level higher than the background currentlevel) immediately after the peak phase may be avoided. However, as alsomentioned above, one or more knee phases may be used in certainembodiments. For example, FIG. 6 generally illustrates an exemplarywaveform 110 that is similar to the waveform illustrated in FIG. 3, butthat includes one or more knee phases 112 immediately after the peakphase 72 but before the dabbing phase 74. As such, the peak phase 72 isfollowed by the one or more knee phases 112, and then the short may beforced with the dabbing phase 74 followed by one or more backgroundphases 70. Although illustrated as having only one knee phase 112 andonly one background phase 70 in FIG. 6, it will be appreciated that morethan one knee phase 112 and/or more than one background phase 70 may beutilized in certain embodiments. In general, the one or more knee phases112 will have a current level higher than the one or more backgroundphases 70 but lower than the peak phase 72. For example, the knee phase112 illustrated in FIG. 6 is at a current level of approximately 125amps while the background phase 70 is at a current level ofapproximately 115 amps and the peak phase 72 is at a current level ofapproximately 400 amps. In other embodiments, the one or more kneephases 112 may have a current level in a range of approximately 125-250amps as long as the current level remains above the current levels ofthe one or more background phases 70.

FIG. 7 illustrates exemplary control logic for implementing the dabbingregime of FIG. 6. The logic, indicated generally by reference numeral114, is substantially similar to the logic 98 illustrated in FIG. 5 butwith an additional step 116 of having one or more knee phases 112 inbetween the peak phase 72 and the dabbing phase 74. In certainembodiments, the peak phase 72, knee phase 112, or dabbing phase 74 maybe replaced with a power source off signal. In particular, the powersupply 10 may be turned off by dropping the current command to zero (ora very low command level such as approximately 1-2 amps or even lowerthan 1 amp), by disabling an engine driving the power supply 10, or byturning off a power source gate signal of the power supply 10. Any oneof the steps of the logic 114 illustrated in FIG. 7 relating to the peakphase 72 (e.g., step 102), the one or more knee phases 112 (e.g., step116), or the dabbing phase 74 (e.g., step 104) may be replaced with thestep of extinguishing the arc by disabling the power supply 10. Forexample, FIG. 8 illustrates exemplary control logic 118 for bypassingany one of these steps to instead send a power off signal to the powersupply 10. In certain embodiments, once the arc has been extinguished, arelatively small current (e.g., approximately 1-2 amps or even lowerthan 1 amp) may be applied, re-enabling the power supply 10 andreigniting the arc, followed by one or more background phases 70 (e.g.,returning to step 108 of the logic 118). In certain embodiments, onceextinguishment of the arc has been initiated, the voltage may bemonitored for a short (because the arc may hold for a few millisecondsdue to capacitance and inductance) and, once the arc has beenextinguished, the relatively small current (e.g., approximately 1-2 ampsor even lower than 1 amp) may be applied, re-enabling the power supply10 and reigniting the arc.

While only certain features of the invention have been illustrated anddescribed herein, many modifications and changes will occur to thoseskilled in the art. It is, therefore, to be understood that the appendedclaims are intended to cover all such modifications and changes as fallwithin the true spirit of the invention.

1. A welding system comprising: a processing circuit configured toprovide a control waveform for a pulsed welding regime, the controlwaveform comprising a peak phase followed by a dabbing phase followed bya background phase, wherein a first voltage level and a first currentlevel of the control waveform during the dabbing phase are less than asecond voltage level and a second current level, respectively, of thecontrol waveform during the background phase, wherein during the dabbingphase the short circuit is broken; and a power conversion circuitconfigured to provide welding power output based upon the controlwaveform.
 2. The welding system of claim 1, wherein during thebackground phase the welding power output has a current level of betweenapproximately 25 amps and approximately 125 amps.
 3. The welding systemof claim 2, wherein during the dabbing phase the welding power outputhas a current level of less than approximately 25 amps.
 4. The weldingsystem of claim 3, wherein the dabbing phase has a duration of betweenapproximately 1 millisecond and approximately 5 milliseconds.
 5. Thewelding system of claim 1, wherein a peak current level of the controlwaveform during the peak phase is greater than the first current levelduring the dabbing phase and the second current level during thebackground phase.
 6. The welding system of claim 1, wherein the dabbingphase resets an arc length between an end of a welding electrode and aweld puddle into which a ball of molten metal is deposited.
 7. Thewelding system of claim 1, wherein the welding output power isclosed-loop controlled during the peak and background phases to maintainone or more target voltages.
 8. A welding system comprising a processingcircuit configured to: generate a pulsed waveform for welding poweroutput, the pulsed waveform comprising a peak phase followed by adabbing phase followed by a background phase, wherein a short circuit isestablished between a ball of molten metal from a welding electrode anda workpiece during the dabbing phase, the short circuit is broken duringthe dabbing phase, and the first current level of the pulsed waveform ismaintained between when the short circuit is established and when theshort circuit is broken during the dabbing phase; and convert incomingpower to welding power based upon the pulsed waveform.
 9. The weldingsystem of claim 8, wherein during the background phase the welding poweroutput has a current level of between approximately 25 amps andapproximately 125 amps.
 10. The welding system of claim 9, whereinduring the dabbing phase the welding power output has a current level ofless than approximately 25 amps.
 11. The welding system of claim 10,wherein the dabbing phase has a duration of between approximately 1millisecond and approximately 5 milliseconds.
 12. The welding system ofclaim 8, wherein a peak current level of the pulsed waveform during thepeak phase is greater than the first current during the dabbing phaseand a second current level during the background phase.
 13. The weldingsystem of claim 8, wherein the welding output power is closed-loopcontrolled during the peak and background phases to maintain one or moretarget voltages.
 14. A welding system comprising a processing circuitconfigured to: generate a first peak phase of a first pulsed waveform ofa welding power output, wherein a first ball of molten metal begins todetach from a welding electrode during the first peak phase; generate adabbing phase of the first pulsed waveform of the welding power output,wherein the dabbing phase follows the first peak phase, a short circuitis established during the dabbing phase, and the short circuit is brokenduring the dabbing phase; generate a background phase of the firstpulsed waveform of the welding power output, wherein the current levelof the first pulsed waveform during the background phase is greater thanthe current level of the first pulsed waveform during the dabbing phase;and generate a second peak phase of a second pulsed waveform of thewelding power output, wherein a second ball of molten metal begins todetach from the welding electrode during the second peak phase, and thesecond peak phase immediately follows the background phase.
 15. Thewelding system of claim 14, wherein the processing circuit is furtherconfigured to: control a voltage level of the first pulsed waveformduring the first peak phase using a closed-loop control regime; controlthe voltage level of the first pulsed waveform during the backgroundphase using the closed-loop control regime; and control the currentlevel of the pulsed waveform during the dabbing phase.
 16. The weldingsystem of claim 15, wherein the current level of the first pulsedwaveform is not increased to break the short circuit during the dabbingphase.
 17. The welding system of claim 14, wherein the welding electrodecomprises a cored wire.
 18. The welding system of claim 14, wherein thecurrent level is between approximately 25 amps and approximately 125amps during the background phase.
 19. The welding system of claim 14,wherein during the dabbing phase the current level is less thanapproximately 25 amps.
 20. The welding system of claim 14, wherein thedabbing phase has a duration of between approximately 1 millisecond andapproximately 5 milliseconds.